Main Street Facility Ammonia Refrigeration System - Executive Summary

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EXECUTIVE SUMMARY 
 
Trinchero Family Estates (Sutter Home Winery) has established a risk management plan according to EPA's regulations (40 CFR Part 68) for the Ammonia Refrigeration System at its Main Street Facility to enhance its already existing safety programs.  Sutter Home is extremely cautious in the handling of all chemicals and is very diligent about safety for its employees and its communities.  Sutter Home staff is highly trained and utilizes modern equipment to provide safeguards.  The Ammonia Refrigeration System, that contains the regulated substance anhydrous ammonia, is used for chilling wine and for cooling down wine storage tanks and maintaining them at a cold temperature.   
 
 
Accidental Release Prevention and Emergency Response Policies 
 
Sutter Home has an emergency response plan in effect to handle potential emergency situations at this facility.  This plan was designed to meet the following objectives: 
 
1.) To save lives. 
2.) To minimize and avoid injuries. 
3.) To p 
rotect the environment. 
4.) To minimize property damage. 
 
Key elements of the Emergency Response Plan include key phone numbers and contact points, plans for evacuation, fire, injury, earthquake, hazardous material spill, and ammonia health hazards  
 
 
Stationary Source and Regulated Substance 
 
The ammonia refrigeration system is made up of two refrigeration plants.  The two plants are very similar.  Both are single stage, comprised of compressors, evaporative condensers, high pressure receivers, pumped recirculators, flooded wine chillers, area coolers, glycol coolers, wine tank jackets, piping, valves and automatic control units.   
 
Each plant contains about 8,000 lb. of anhydrous ammonia that continuously circulates through the system.  Vaporization of ammonia at different points of the system provides the needed cooling effect.   
 
Liquid ammonia is pumped from a recirculator to various tank jackets, wine chillers or other cooling points.  By controlled vaporization of liquid ammonia 
the desired cooling effect is obtained.  Vaporization is achieved by either passing the liquid ammonia through a narrow passage (an expansion valve) or by controlling the pressure (which in turn controls the vaporization rate) of a flooded heat exchanger.  From these loads ammonia vapor (which often is mixed with liquid ammonia) returns to the recirculator.  The recirculator acts as a separator.  The liquid from the returned ammonia accumulates at the bottom of the recirculator, from where the pumps take suction.  The vapor in the upper part of the recirculator gets drawn by the compressors. 
 
The compressors pressurize ammonia vapors considerably.  In this process the ammonia gas heats up as well.  The discharge of the compressors passes through the evaporative condenser, where cold water on the external side of the cooling tubes causes the ammonia temperature to drop below its condensation point and causes the ammonia gas to turn into liquid.  The liquid from the evaporative condense 
r collects in the high-pressure receiver.   
 
As the refrigeration system operates the liquid level in the recirculator drops.  The lost ammonia is replenished by the liquid in the high-pressure receiver.  The level switches on the recirculator cause the automatic control valves to open and allow liquid ammonia, which is at higher pressure in the receiver than the pressure in the recirculator, make-up the ammonia taken by the compressors. 
 
Ammonia refrigeration system is equipped with many safety features.  System control is achieved primarily by local automatic control units that control liquid level, temperature and pressure.  The compressors are equipped with shutoff mechanisms based on pressure (high and low) and temperature.  Relief valves are installed on all the vessels and compressors. Each plant is also equipped with a Fire Department Dump Station, which allows, in case of an emergency, for the ammonia to be safely drained from the plant.   
 
The system is controlled automatical 
ly and under normal conditions there is little need for the operators to intervene with the operation of the system.  The operators, however, check the system periodically and provide the needed test, inspection and maintenance activities.  All elements of the system are subjected to a periodic inspection, testing and preventative maintenance program. 
 
 
Hazard Assessment Summary 
 
Worst Case Release Result Summary 
Scenario Description: It is assumed that 8,000 lb. of liquid ammonia (the entire content of one refrigeration plant) is released from the largest vessel.  This is a conservative assumption, because the entire content of the plant is never within one vessel.  Per the instructions of the regulation, the release is postulated to occur in 10 minutes.  The most pessimistic meteorological conditions were used as specified in the regulation.  The reference table included in EPA's RMP Guidance for Ammonia Refrigeration was used to determine the maximum downwind distance to 200 ppm.  T 
he result shows that offsite areas may be affected. 
 
Alternative Release Result Summary 
Scenario Description: A release of liquid ammonia from a failed pump seal or from a leaking valve packing in a liquid line at the high pressure side of the system as an alternative release scenario that represents a realistic, but yet very unlikely event.  These scenarios model a leak from valve packing or a pipe connection.  However, the selected hole diameter is very conservative given the typical opening sizes experienced in similar situations.  The meteorological conditions specified in the regulation for alternative scenarios were used.  The reference table included in EPA's RMP Guidance for Ammonia Refrigeration was used to determine the maximum downwind distance to 200 ppm.  The downwind distance for this scenario is significantly less than that for the worst case scenario.  However, in this case also, offsite areas may be affected. 
 
 
Accidental Release Prevention Program and Chemical-Specifi 
c Prevention Steps 
 
Sutter Home has implemented a Process Safety Management (PSM) program at the Main Street Facility to manage the safety aspects of the Ammonia Refrigeration System.  In addition, common industry standards, policies, and procedures are utilized to ensure safe practices are being performed.  This includes common practices outlined by industry sources.   
 
 
Five Year Accident History 
 
There have been no reportable releases of ammonia at the facility in the past 5 years that had lead to an injury, fatality or environmental impact. 
 
 
Planned Changes to Improve Safety 
 
Several process and management system improvements are being considered and implemented as a result of the technical studies done in the course of the development of the PSM and RMP Programs.  The main focus of the improvements is on issues recommended to be included in the operating and maintenance procedures and specific tests, inspection and maintenance activities to be conducted as part of the mechanical  
integrity program.  These modifications will be implemented in a short time.
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